In general, dialysis treatment is performed by using a dialysis treatment apparatus including a blood circuit for extracorporeally circulating the blood of a patient, a dialyzer connected to a halfway point of the blood circuit, a peristaltic blood pump, and a dialysis-apparatus body capable of performing ultrafiltration while performing hemodialysis treatment in which dialysate is introduced into or delivered from the dialyzer. Typically, dialysis treatment performed with such a dialysis treatment apparatus continues for about four hours and is given every other day. Therefore, the hemodynamics of the patient during the treatment changes significantly. In particular, it is important to efficiently and assuredly prevent the decrease in blood pressure caused by the removal of excessive water (ultrafiltration).
Furthermore, many of patients who need to take dialysis treatment also suffer from cardiovascular complications such as arrhythmia. Therefore, abnormality in circulatory dynamics and the cause thereof need to be grasped by monitoring the heartbeat, the pulse, and so forth. One of general measures for monitoring such information on the heartbeat and the pulse of the patient is the use of an electrocardiograph capable of measuring an electrocardiogram. For example, during blood purification treatment, at least a pair of electrodes (electrocardiogram-measuring devices) are closely attached to the patient, and the electrocardiogram of the patient is measured on the basis of the potentials of the electrodes.
On the other hand, in blood purification treatment, an arterial puncture needle and a venous puncture needle are stuck into the patient, and the blood of the patient is collected through the arterial puncture needle and is extracorporeally circulated through a blood circuit so that the blood is purified. Then, the blood thus purified needs to be returned to the patient through the venous puncture needle. Hence, in the process of extracorporeal blood circulation, the puncture needles may each accidentally come off the site of the patient where the needle is stuck when, for example, the patient makes any move. In particular, if the venous puncture needle comes off, some blood may leak to the outside. To detect such coming off of the puncture needle, the known art employs detection of blood leakage from the puncture needle by using a blood leakage sensor or the like (see PTL 1, for example).